Effect Of Nano Al₂O₃-B （Boron） On Dezine Corrosion Resistance And Cutting Performance Of Lead-free Brass

Lead brass（Cu-Zn-Pb alloy）is one of the most widely used materials in mechanical manufacturing industry,Because of its excellent mechanical properties and machinability good cutting property and corrosion resistance.However,lead is toxic and lead spillage is harmful to environment and health during the use.Therefore,lead-free cutting Huang Tongcheng is the focus of research.In this paper,a powder metallurgy（P/M）method is proposed to improve the cutting performance of brass by adding Al₂O₃ with a chip breaking effect.Through microstructure observation,chip analysis,dezine depth calculation and mechanical property test.To clarify the effect of Al₂O₃ content on the performance of brass was clarified.After adding nanoscale Al₂O₃ to brass.With the increase of Al₂O₃ content,the twinning content increased,grain size decreased,But the cutting performance,hardness and yield strength increased significantly.However,the wettability between Al₂O₃ and brass is poor.So it is easy to reunite in brass,with the increase of Al₂O₃ content,the Al₂O₃ agglomeration in the material increases,which leads to the the decrease of the density and the corrosion resistance of the sample.However,defects are likely to become fracture sources during tensile process and affect the mechanical properties of specimens,the tensile strength and elongation of the sample are reduced.Because boron can occupy or diffuse into two vacancies,that can slow down the migration speed of double vacancy,reduce the corrosion rate and dezine coefficient.Adding a certain amount of B in brass can improve the corrosion resistance of brass,at the same time B can purify brass matrix,which may increase the elongation of materials.In this paper,the effect of B content on the properties of brass has been studied,through the analysis of the properties of the sample.It is found that the conductivity of the sample,the anti dezine corrosion resistance and the elongation of the sample have been greatly improved by adding 0.01wt%B in the brass.The conductivity increased to 27.3%IACS;the depth of dezine layer decreased by 37%,the elongation rate increased by 31%.The comprehensive properties of brass were obviously improved,with the increase of B content,the boride impurities produced reduced the comprehensive properties of the materials.0.01wt%B is added to alumina brass（0.01B-Al₂O₃/Cu40Zn）to improve the anti dezine corrosion resistance and elongation of alumina brass.It is found that the improvement effect of B on Al₂O₃/Cu40Zn performance is not obvious or even negligible with the increase of Al₂O₃ content.The main reason is that with the increase of Al₂O₃ content,the Al₂O₃ agglomeration group increases and defects increase,resulting in the decrease of Al₂O₃/Cu40Zn performance.To improve the wettability between Al₂O₃ and brass,in this paper,B（OH）₃ is used to modify the surface of Al₂O₃,to prepare the Al₂O₃ modified powder which coated with Al₁₈B₄O₃₃.To improve the wettability between Al₂O₃ and brass,at the same time,the effect on other properties of Al₂O₃/Cu40Zn was reduced.The experimental results show that the brass sample prepared by the modified Al₂O₃ powder has a certain increase in density,electrical conductivity,hardness,and good cutting performance,the ability to resist dezunzine corrosion is also greatly improved,and the thickness of dezunzine layer decreases by 38.3%.After modification,the wettability between Al₂O₃ and brass is enhanced and the defects in the sample are less than that of unmodified.The yield strength of modified alumina brass（Al₂O₃/Cu40Zn）is basically consistent with that of Al₂O₃/Cu40Zn,but the tensile strength and elongation have been improved clearly and the elongation rate is increased at most.26%.